Abstract

Barracuda and Caratinga fields, with 1.1 GBOE reserves, are one of the main deep-water discoveries of the late 80's and early 90's in Campos Basin, southeast of Brazil. At that time, as it is nowadays, the economic feasibility of deep-water development projects was very much dependent on the high productivity of the wells. In despite of the quite good petrophysical properties, the thickness of the reservoirs did not provide enough productivity to make such projects feasible. The horizontal wells technology came over to improve productivity indexes, making possible the development of these giant fields. The high quality of the seismic data would help the positioning and the geosteering of the horizontal wells. The reservoirs of the fields are sandstone turbidites and have quite distinct depositional styles and structural features. Hence, different well patterns and completion strategy were used for each one. The reserves will be produced by 32 wells and, to maintain the reservoir pressure, 22 water injection wells will be used. To reduce the reservoir uncertainty, a production anticipation project -Pilot Project- was planned. Eleven exploratory wells were completed on the main reservoir units and blocks. These would permit the observation of the reservoir behavior and the checking of the reservoirs hydraulic compartmentalization, once the development wells were drilled. At the end of the Drilling Phase, the results are honouring the project initial assumptions. The Original Oil in Place as well as the productivity / injectivity indexes were confirmed. The reservoir pressure dynamic data showed that the assumed hydraulic model to set the development plan was very close to the verified one, regarding the horizontal and vertical connectivities. This paper focuses on the key factors that enabled a successful project implementation and on the strategy used for the reservoir development of these deep-water offshore fields.

Introduction

Barracuda and Caratinga deep-water giant oil fields are located on the south-central part of Campos Basin, southeast of Brazil, about 90 km from the Rio de Janeiro State coast, in water depths of 600 to 1,100 meters for Barracuda and 850 to 1,350 meters for Caratinga (Fig. 1). The reservoir depths range from 2400 to 3200 m. These fields comprise OOEIP volumes of 4.2 GBOE and reserves of 1.1 GBOER within high quality siliciclastic turbidite reservoirs from the Tertiary. The average gravity of the oil ranges from 20 to 26° API. From the total reserves, about 70% of them are in Barracuda and 30% in Caratinga Field. Barracuda Field reserves are divided in an Oligocene / Miocene reservoir, called MRL330 and an Eocene / Paleocene reservoir, called ENCOBR. On the other hand, most of Caratinga field reserves (about 83%) are within a Lower Oligocene reservoir called CRT100. The rest of Caratinga Field reserves are within Oligocene/Miocene, MRL330 and Oligocene reservoirs, MRL600 and MRL700. Barracuda Field was discovered in 1989 and Caratinga, the first Campos Basin field discovered using 3D seismic, was discovered in 1994. In 1997, using exploratory wells already drilled to produce from the main blocks, a Pilot Production Project started, through the FPSO P-34 (Fig. 2).

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